This invention relates to active and semiactive radars, and more particularly to radar-receiver signal processors matched to coherently pulsed radar signals in a moving-target environment, and more particularly to techniques for providing enhanced signal-processing gains in such signal processors.
Active and/or semiactive radar-receiver signal processors can be xe2x80x9cmatchedxe2x80x9d to coherently pulsed radar signals in a moving-target engagement. This type of processor typically updates hypothesized own-ship/target differential-Doppler compensation (range-rate aiding) at a coherent processing interval (CPI) rate to develop a detection statistic via simple zero-order noncoherent post detection integration (PDI). This CPI-rate compensation of hypothesized differential own-ship/target Doppler prohibits the application of overlapped-CPI noncoherent PDI processing, since desired-signal coherence within the overlapped observation intervals will be destroyed.
A Noncoherent Gain Enhancement (NGE) algorithm technique, in accordance with an aspect of the invention, implements noncoherent integration, over one or more hypothesized range-Doppler trajectories, of an enlarged signal set obtained by integration over a longer time interval, and/or from using overlapped coherent processing intervals (CPIs). Multiple hypothesized target accelerations may be employed, which may be constant or may be time-varying, for example corresponding to a hypothesized target maneuver, such as a turning maneuver. The use of multiple hypothesized target accelerations allows the integration over a longer time interval. This technique of noncoherent integration provides a significant improvement, over conventional radar processing, in target detection and target-parameter estimation. The NGE algorithm provides, over the same observation (PDI) interval, noncoherent integration of a much larger number of coherently processed signals to effect greater signal processing gains. This is in addition to the integration over a longer time interval (the elongated PDI interval), which as noted above may employed because of the use of multiple hypothesized range-Doppler trajectories that may involve multiple hypothesized target accelerations. Sliding window integration may be employed to allow generation of output data at smaller time intervals than the elongated PDI interval.
According to an aspect of the invention, a method of processing data in a sensor system that received signal returns from pulsed coherent transmitted signals, includes forming a plurality of range-Doppler maps; and noncoherently integrating the results of the range-Doppler maps along a hypothesized range-velocity trajectory that is a function of a hypothesized acceleration, thereby producing combined range-Doppler results.